function initRollovers() {
    if (!document.getElementById) return

    var aPreLoad = new Array();
    var sTempSrc;
    var aImages = document.getElementsByTagName('img');

    for (var i = 0; i < aImages.length; i++) {
        if (aImages[i].className == 'on') {
            var src = aImages[i].getAttribute('src');
            var ftype = src.substring(src.lastIndexOf('.'), src.length);
            var hsrc = src.replace(ftype, '_on'+ftype);

            aImages[i].setAttribute('hsrc', hsrc);

            aPreLoad[i] = new Image();
            aPreLoad[i].src = hsrc;

            aImages[i].onmouseover = function() {
                sTempSrc = this.getAttribute('src');
                this.setAttribute('src', this.getAttribute('hsrc'));
            }

            aImages[i].onmouseout = function() {
                if (!sTempSrc) sTempSrc = this.getAttribute('src').replace('_on'+ftype, ftype);
                this.setAttribute('src', sTempSrc);
            }
        }
    }
}

try {
    window.addEventListener("load", initRollovers, false);
} catch(e) {
    window.attachEvent("onload", initRollovers);
};
